Motor driven value

ABSTRACT

An easy-to-assemble motor-adjustable throttle valve ( 12 ) for fluid channels ( 11 ), especially in motor vehicle air conditioning systems, which can be obtained when a geared motor ( 14 ) is integrated in the setting stem without causing an unacceptable reduction of the remaining clear channel cross-section. A built-in housing fitted with a high-speed small servomotor and provided with a strongly reducing shaft gear ( 28,31 ) disposed in the axial extension of the housing is radially inserted through a side wall of the channel and coaxially inserted into a pot-shaped tapered section ( 19 ) of one end of the setting stem, the output wheel of the shaft gear being formed on the inner covering surface of said section.

[0001] The invention relates to a valve according to theprecharacterizing clause of claim 1.

[0002] A valve of this type, depending on its dimensions, is usedparticularly in supply-air and waste-air ducts, for example for thethrottling of fresh air in the air-conditioning of stationary or mobilespaces, but also, in general, for influencing the throughflow during theflow transport of flowable materials. For this purpose, the valve ismounted in the inner cross section of the duct about a pivot axis andcan be set into different angular positions with respect to thedirection of flow. When it is oriented parallel to the direction offlow, the throttle action is minimal, being provided only by theinstallation dimensions of the valve. By contrast, when the latter isoriented transversely to the direction of flow, the smallest freeresidual cross section remains. The geometry of the valve usually hasexactly the cross-sectional form of the duct and, if necessary,depending on the flow medium, sealing lips along its circumference, sothat, when the valve is oriented transversely to the longitudinal extentof the duct, the entire inner cross section of said duct is shut offhermetically.

[0003] The valve drive conventionally takes place via an electricservomotor, but, in surroundings where there is an explosion hazard,also by means of a hydraulic or pneumatic fluid motor. For this purpose,an actuating shaft connected in a rotationally rigid manner to the valveand mounted in duct side walls located opposite one another transverselyto the longitudinal extent projects out of one of the side walls tooutside the duct to the servomotor for the valve movement. This isbecause considerable torques have to be applied for valve adjustment andthen for holding the valve in its desired angular position under theload of the medium flowing up in the duct; whereas an installation of acorrespondingly large-dimensioned servomotor into the interior of theduct would reduce the useful cross section of the latter unacceptably.On the other hand, the externally arranged valve drive markedlyprojecting beyond the outer cross section of the duct there may bedisturbing for the operational surroundings, particularly in the case ofsystems with narrow dimensioning. The space for the valve drive locatedoutside the duct is then often not readily available, particularly forthe subsequent installation of such a throttle valve at an operationallypredetermined point of a complex pipeline system, such as in the enginespace of a motor vehicle, for regulating the air-conditioning of thepassenger cell. This may then mean that a complicated, but otherwisefunctionally disturbing lever mechanism has to bridge the distance fromthe motor to the valve mounting.

[0004] The object on which the invention is based is therefore, then, todesign a motor-operated valve of the generic type, particularly forfluid conduction systems, such as are encountered in motor vehicleair-conditioning systems, to the effect that it, together with itsdrive, can be used without difficulty, even subsequently.

[0005] This object is achieved, according to the invention, in that thegeneric valve is also designed according to the characterizing part ofthe main claim. According to this, a very highly reducing geared motoris inserted into the interior of a hollow shaft of the valve. The highgeared reduction makes it possible to use a very high-speed andtherefore small-build motor, such as is available as a highlycost-effective mass product, for example, in the form of a low-voltagedirect-current servomotor. In spite of the unusually high reduction, thegear can be designed with an extremely small build when it is conceivedas what may be referred to as a wave gear, such as is described infunctional terms, for example, in the contribution “Genial einfach”[“Ingeniously simple”] by H. Him in ANTRIEBSTECHNIK 11/1996 pages 48-51,to the full content of which reference is made here in order tosupplement the disclosure of the present invention. Preferably, thecommercially available micromotor is embedded axially into aninstallation housing in the form of a thin-walled bowl, which hasengaged over it in turn, on the opposite side, the hollow shaft of thevalve. The coaxial gear arranged in the axial extension of the motor inthe hollow shaft utilizes a wall part, projecting axially above thebottom of the installation housing, as a supporting wheel and a part ofthe hollow shaft itself, which is axially adjacent thereto, as an outputwheel for the tappet wheel of the wave gear and consequently has aparticularly compact construction.

[0006] The diameter of such a small-build motor/gear combination is atmost one third of the diameter of ventilation ducts normally to beencountered in motor vehicle air-conditioning, and the axial length ofthe motor/gear combination is of the order of magnitude of typicallyhalf the duct diameter, so that the reduction in cross section occurringwhen the actuating drive is installed into the very interior of a ductof comparatively small diameter is justifiable. The thinner the duct tobe shut off is, the further the geared motor of standardizedconstructional length engages radially into the duct; in the case of avery small duct, the geared motor is then arranged in a continuoushollow shaft as the valve actuating shaft, without the reduction incross section becoming unacceptable—in the case of larger ducts, such asthose with customary inner dimensions of 120×120 mm, the valve shaft,then widened in a tulip-shaped manner only over a correspondingly shortpart of its axial length, no longer has any bearing in any case.

[0007] The motor may be designed as a bar-armature direct-current motor,but also as a stepping motor. The small-volume installation housing withits integrated functions as a bearing journal for the actuating shaftend widened in the form of a bowl, as a housing with a supporting wheel,fixed with respect to the apparatus, for the wave gear and, ifappropriate, also as a substrate for electrical conductors, such aspotentiometer slide tracks and their connecting conductor tracks, isadvantageously a plastic injection molding, for example manufacturedfrom a duroplastic.

[0008] A motor-adjustable throttle valve, mountable in a simple way, forfluid ducts, such as have to be encountered particularly in motorvehicle air-conditioning, is thus obtained, in the case of a gearedmotor integrated according to the invention into the valve actuatingshaft, without any unjustifiable weakening of the remaining thin ductcross section, when an installation housing equipped with a high-speedsmall servomotor is equipped in the axial extension of the motor spacewith a very highly reducing wave gear and is inserted into a hollowvalve actuating shaft, on the inner surface area of which is formed theoutput wheel of the wave gear.

[0009] With regards to further properties and advantages and alsofeatures and developments of the invention, reference is made not onlyto the further claims, but also to the following description of thepreferred exemplary embodiment of the solution according to theinvention, said exemplary embodiment being sketched, not entirely trueto scale, in the drawing and with restriction to what is functionallyessential. The single FIGURE of the drawing shows, in a truncatedlongitudinal section through a ventilation duct of rectangular innercross section, the installation of the servomotor into the partiallyhollow shaft of the throttle valve oriented exactly in the passageposition.

[0010] A fluid duct 11 of rectangular cross section here has installedin it a throttle valve 12, the contour of which has the same geometry asthe duct cross section and therefore shuts off the duct throughflow whenit is oriented transversely to the drawing plane. By contrast, in thedepicted position parallel to the longitudinal axis of the duct 11, thecross section of the latter is reduced only by the comparatively verysmall installation dimensions of the valve 12, together with itsservomotor 14, integrated in the hollow shaft 13 of said valve, with thereduction gear 15.

[0011] In the preferred example illustrated, the valve 12 has, on bothsides of its shaft 13, in each case a wing in a common plane. The twowings of the valve 12 are formed in one piece with its common shaft 13,preferably produced in one part by plastic injection molding. To theextent that the axial length of the geared motor 14-15 is smaller thanthe diameter of the duct 11 in the direction of the valve actuatingshaft 13, the shaft 13 does not need to occupy over its entire lengththe volume of a hollow shaft. For the example illustrated, to reduce theinstallation dimensions, the shaft 13 has a tulip-shaped configurationin the longitudinal section, with a stem of greater or lesser length asa continuation of its hollow-cylindrical orifice, that is to say, onlyover a part of the shaft length as is evident from the sectionalillustration of the drawing, hollow so as to open in a bowl-shapedmanner toward the adjacent side wall 16 and otherwise compact, hererestricted to the minimum cross section necessitated by the bendingmoment requirements.

[0012] This stepped or continuously hollow pivoting shaft 13 for theangular position of the valve 12 inside the duct 11 is mounted, on theone hand, in a side wall 18 of the duct 11 by means of a journal 17. Along bowl-shaped installation housing 22 for the geared motor 14-15projects from the opposite side wall 16 radially into the interior ofthe duct 11 and serves as a bearing journal, fixed with respect to theduct, for the adjacent end of the shaft 13, said end surrounding saidgeared motor and being hollow-cylindrical here or widened radially in abowl-shaped manner. To reduce the friction, the shaft bowl 19 does notrest against the in each case radially opposite cylindrical surface areaover the full surface, but only with at least one rib 20 running aroundon its inner surface area or on the outer surface area of the housing22. Thus, the valve 11 is mounted pivotably with its hollow shaft 13 onthe installation housing 22 for the geared motor 1415 about the axis 23of the latter. The motor 14 itself is simply inserted axially, securednonpositively or positively against rotation, into the end face of theinstallation housing 22, said end face being opened toward the adjacentside wall 16. When the installation housing 22 equipped with the gearedmotor 14-15 is being installed, a collar 24 running radially around theinstallation orifice 34 on the outside is fastened in an orifice 25 inthe duct side wall 16, through which, during assembly, the valve 12 thusequipped with its drive can be introduced radially into the duct 11.Expediently, as outlined, the collar 24 is enlarged in the radialdirection so far beyond the cross section of the installation housing 22that, together with the installation mounting of the geared motor 14-15,said collar at the same time also serves as a cover for closing theassembly orifice 25 which does not necessarily have to be circular andthe largest diameter of which is somewhat larger than the overalldimension, radial to the shaft 13, of the valve 12 to be introducedhere.

[0013] For the particularly high, but compact-build reduction of therotational movement of the motor output shaft 27, a wave gear 15 isformed in front of that end face of the installation housing 22 which isremote from the mounting wall 16 for the geared motor 1415. Its wavegenerator 26, as it may be referred to, which is nonround (preferablyelliptic in axial cross section or, as assumed here for the drawing,triangular) and which is connected rotationally to the output shaft 27of the motor 14, has the effect, in a way known as such, that a spokedtappet wheel 28 is peripherally deformed radially, so that only anazimuthally short region (on the left in the drawing) of its toothedouter ring, which may be referred to as the flexible band 29, is inengagement both with the toothing of a supporting wheel 30 fixed withrespect to the apparatus and also with the toothing of an output wheel31 fixed with respect to the valve. These toothings are preferablyoriented radially, as outlined; in principle, however, they may also beoriented axially, for example, in the manner of contrate wheels.

[0014] Preferably, as outlined, the supporting wheel 30 lies in thedirect axial extension of the hollow cylindrical wall of the motorinstallation housing 22 on the inner surface area of a gear housing 32integrally formed coaxially here, the output wheel 31 lying on thatregion of the inner surface area of the hollow shaft 13 which isadjacent to the bottom of the valve shaft bowl 19. As a result, thetappet wheel 28 rolls within the supporting wheel 30 at the angularspeed of the motor shaft 27, but takes along the output wheel 31 andtherefore the valve shaft 13 only at the very greatly reduced angularspeed according to the slight difference in the number of teeth, forexample, between the supporting wheel 30 and the output wheel 31.Highspeed motor rotation is thus converted into the high torque of aslow valve adjustment.

[0015] For a feedback of the current angular position of the valve 12 inthe duct 11, a rotary angle encoder 33 is installed in a radiallywidened region between the outer surface area 21 of the motor housing 22and the shaft bowl 19 near the end face orifice of the latter. Saidencoder may be an incremental or coded digital counting system; orsimply, as outlined, an analog potentio metric system with at least onecontact brush on at least one circulating resistance track. The latter,including its conductor track to externally accessible connecting plugson the collar 24 of the installation housing 22 can then be integrated(not indicated in the drawing) into the plastic surface area 21 of thehousing 22 or of the shaft bowl 19 mounted on said surface area, by thetechnology of what is known as the Molded Interconnected Device (MID).However, it is more expedient, since, for example, it is accessible in asimpler way for an exchange which may possibly be necessary, to have aconventional solution with a separately produced and here mountedsubstrate plate for the count marking or for the resistance tracks. Thissubstrate may be designed as an annular disk oriented radially to theaxis 23 or as a flexible sleeve bent concentrically to the axis 23 andbe secured in a stationary manner on the outer surface area 21 of theinstallation housing 22 or peripherally in the end-face widening of thehollow-shaft bowl 19, with contact brushes held opposite and radially oraxially oriented correspondingly.

[0016] For assembly, the throttle valve 12 is only to be introduced,with its integrated shaft 13 widened at least over part of its axiallength to form a bowl, radially through the orifice 25 in a duct sidewall 16 into the duct cross section and be plugged with its bearingjournal 17 into the opposite wall 18, whereupon the installation housing22 prefitted with the geared motor 1415 can be introduced axially as asecond bearing journal into the shaft bowl 19, as a result of which theassembly orifice 25 is at the same time closed by the housing collar 24of the motor 14. Even more expediently, the valve 21, together with itsat least partially hollow shaft 13, and the geared motor 1415 in itsinstallation housing 22 are preassembled externally to form a singlemanageable subassembly, as illustrated in the drawing, by way ofexample, by the engagement of the radial bearing rib 20 into a snapingroove on the outer surface area of the housing 22, which may then serveat the same time for securing the shaft 13 axially in the oppositedirection to the mounting of the journal 17.

[0017] The contact lugs 35, projecting from the bearing plate of themotor 14, for the electrical feed of the motor 14 are easily accessiblethere for the connecting cabling in the housing installation orifice 34.The latter may be closed by means of a cover 36 in the form of a plug orof a shallow bowl, preferably simply to be inserted nonpositively,preferably with an integrated plug cage. For matching to differentmotors 14 in terms of the position of contact lugs 35, the cover 36 thenneeds only to be equipped with a different plug cage. This isexpediently designed at the same time for electrical access to therotary angle encoder 33, so that no separate contact means have to beattached for connecting the latter to the control periphery.

1. A motor-actuable valve (12), in particular for influencing the crosssection of a fluid duct (11), characterized in that the valve (12) isequipped with a shaft (13) which is hollow over at least part of itsaxial length and is part of the output wheel (31) of a geared motor (14,15) arranged in said hollow shaft.
 2. The valve as claimed in claim 1,characterized in that, on the one hand, the shaft (13) integral with itand, on the other hand, an installation housing (22) for the motor (14)and reduction gear (15) are produced by plastic injection molding. 3.The valve as claimed in claim 1 or 2, characterized in that the shaft(13) consists in a tulip-shaped manner of a solid region of smalldiameter and, following the latter axially, of a bowl (19) opened in themanner of a blind hole, but of substantially larger diameter.
 4. Thevalve as claimed in one of the preceding claims, characterized in thatthe shaft (13) is mounted, on the one hand, by means of a journal (17)in a side wall (18) of the duct (11) and opposite, with an end widenedtoward a bowl (19) on an installation housing (22), coaxial to the valveshaft (13), for the geared motor (14-15) which is itself held on theopposite side wall (16) of the duct (11).
 5. The valve as claimed in thepreceding claim, characterized in that the motor (14) is held in aninstallation housing (22) and the latter is held in the side wall (16)of the duct (11) by means of a continuous collar (24), with an assemblyorifice (25) being closed.
 6. The valve as claimed in one of thepreceding claims, characterized in that a latching connection isprovided between the installation housing (22) equipped with the gearedmotor (14-15) and the valve shaft (13) equipped with the thus completedhousing (22).
 7. The valve as claimed in one of the preceding claims,characterized in that the geared motor (14-15) is equipped in the axialextension of the motor (14) with a wave gear (15), the tappet wheel (28)of which is in engagement over a circumferential part of the toothing ofits flexible band (29) not only with the output wheel (31) fixed withrespect to the shaft, but also with a supporting wheel (30) which isoffset axially relative to said output wheel and which is provided onthe housing (22) coaxially to the shaft (27) of the motor (14) held inthe installation housing (22).
 8. The valve as claimed in one of thepreceding claims, characterized in that a digital- or analogue-operatingrotary-angle encoder (33) is arranged between the motor (14) and thebowl-shaped widening of the valve shaft (13).
 9. The valve as claimed inthe preceding claim, characterized in that the surface area of theinstallation housing (22) and/or of the shaft bowl (19) is or carriesthe substrate for electrically conductive encoder structures.
 10. Thevalve as claimed in one of the preceding claims, characterized in thatit is arranged in the air duct (11) of a motor vehicle air-conditioningsystem.